irule rewrite

Hi, We have a web application that has been published via our big-ip 11.5.1.

Here to situation, we have two web app on the same server iis server

ex.

Sometime the application /app1 return the internal server name as url of the /app2. e.g. (instead of ) I would like to trap and rewrite this url. How do i proceed? it has to be imperceptible to the user. mut be rewrite to

Thanks